Preference gives more consistent judgments than oddity only if the task can be modeled as forced choice

Area of Science:

• Sensory Science
• Psychophysics
• Decision Theory

Background:

• Previous studies indicated higher consistency in preferring tap water over identifying it as the odd sample.
• This observation was often attributed to greater sensitivity in hedonic (preference) judgments compared to oddity judgments.

Purpose of the Study:

• To re-evaluate the interpretation of earlier findings concerning preference and oddity judgments for water samples.
• To investigate the role of statistical decision rules in explaining observed judgment consistencies.

Main Methods:

• Replication of an earlier experiment involving preference and oddity judgments of distilled and tap water.
• Inclusion of new conditions where the decision structure of preference tasks mirrored that of oddity tasks.
• Application of the Thurstone-Ura model for triangle judgments to analyze performance differences.

Main Results:

• Performance in new conditions with identical decision structures was not superior to explicit oddity responses.
• The Thurstone-Ura model accurately predicted results, highlighting the statistical power differences between judgment tasks.
• A model fitting all data suggested a uniform sensitivity (d') between water types, with 25% preferring distilled water.

Conclusions:

• Observed consistencies in water judgments are explained by statistical properties of decision rules, not solely by judgment sensitivity.
• The statistical power of different experimental designs significantly influences perceived performance in sensory discrimination tasks.
• A substantial minority of individuals exhibit a preference for distilled water over tap water, independent of discrimination ability.